Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 282301

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
601 PM CDT THU APR 28 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 339 PM CDT Thu Apr 28 2016

Still expect a dry night as upper ridge approaches the area from the
west and surface low moves over Indiana moves off to the east.
Clouds currently across northern Missouri and central Illinois will
slowly move south through the night as the low moves to the east.
Lows tonight will be slightly cooler than MOS guidance, particularly
where clouds have kept temperatures down today.


.LONG TERM...  (Friday through Next Thursday)
Issued at 339 PM CDT Thu Apr 28 2016

...Friday through Sunday...

Not too much change to going forecast as showers and thunderstorms
will begin to overspread the area on Friday.  It still appears that
likely or categorical PoPs will be needed Friday night into
Saturday morning as strong moisture convergence will lie
underneath decent ascent ahead of mid level trough. There is some
differences between the ECMWF/NAM vs. the GFS with the ECMWF/NAM
showing a slightly more northerly track with the surface low on
Saturday evening than the GFS. The ECMWF/GFS could bring more of a
severe weather threat, so will need to watch this closely. The
chance of thunderstorms will linger into Sunday before the upper
low moves out of the area.

...Monday through Thursday...

While the details differ, the overall idea of the GFS and ECMWF
is the same with the upper pattern becoming more amplified next
week.  Shortwave trough will move southeast out of the Canada early
next week and phase with upper trough moving east out of the
southwest CONUS. This will cause northwesterly flow aloft to
develop by midweek. Rain chances look minimal at this point in the
northwesterly flow with near normal temperatures as the GFS Mean
ensemble and the ECMWF 850mb temperatures will be in the 5-10C



.AVIATION...  (For the 00z TAFs through 00z Friday Evening)
Issued at 527 PM CDT Thu Apr 28 2016

Low level cloudiness will continue at UIN tonight and Friday with
the ceiling dropping into the MVFR catagory late tonight and
continuing MVFR at least through the morning hours. It appears
that these low level clouds will remain north of COU and the St
Louis metro area tonight. VFR, low-mid level cloudiness will
spread into COU and the St Louis metro area by Friday afternoon as
moisture spreads into the area ahead of an approaching storm
system in the southern Plains and north of a warm front. Showers
may move into COU and the St Louis metro area as early as Friday
afternoon, but more likely Friday evening. West-northwest surface
winds will become light this evening, then veer around to an
easterly direction by Friday afternoon as they gradually

Specifics for KSTL: Northwest wind will become light this evening,
then gradually veer around to an easterly direction and increase
to around 8-10 kts Friday afternoon. Just some mid-high level
clouds tonight and Friday morning, then the cloud ceiling will
gradually lower Friday afternoon and evening as showers move into
STL late Friday afternoon or evening. Cigs and vsbys may lower
into the MVFR catagory Friday evening with these showers and as
the low levels saturate.





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